Lobby pressurisation (lift / stair)
Pressurised lift, stair and fire-fighting lobbies: leakage to the floor, to the stair (with the air coming in from a pressurised stair counted) and to the lift shaft, the fire-floor lobby door open at the air speed, the stair > lobby > floor hierarchy, door forces, a relief damper per lobby and the fan sized for the worst case.
What it does
Checks it performs
Sample report
Inputs, results with basis, checks, worked example, drawing and the standards list. Read it before you pay.
Also searched as
lobby pressurization calculation; fire fighting lobby pressurisation; lift lobby pressurization fan; BS EN 12101-6 lobby class B; pressurised lobby air quantity. The same calculation, the same clauses — one tool for fire fighting design under the Indian codes (NBC, IS, CPWD) or the international ones (IEC, NFPA, ASHRAE, EN).
Standards applied
| Reference | Title | Used for |
|---|---|---|
| NBC 2016 Part 4 | National Building Code — Fire and life safety | Occupant load (Table 5), exit width (Table 22), travel distance (Table 21), stair widths |
| BS EN 12101-6:2005 | Smoke and heat control systems — Specification for pressure differential systems — Kits | System classes A–F, design pressure differences and open-door air speeds, door-opening force, leakage areas of doors / windows (Annex A), calculation method |
| BS EN 12101-13:2022 | Smoke and heat control systems — Pressure differential systems (PDS) — Design and calculation methods, installation, acceptance testing, routine testing and maintenance | Design and calculation of pressurised stairs, lobbies and lift wells; commissioning (pressure difference doors closed, air speed doors open) |
| NFPA 92 (2021) | Smoke control systems | Pressurisation and smoke-exhaust design and acceptance |
| NFPA 101:2021 | Life Safety Code | Means of egress (international option) |
| ASHRAE Handbook of Smoke Control Engineering (2012) | Klote, Milke, Turnbull, Kashef, Ferreira — Handbook of Smoke Control Engineering | Flow through leakage paths, wall / floor leakage ratios, stack effect in pressurised stairwells and lift shafts, door-opening force |
| BS 9999:2017 | Fire safety in the design, management and use of buildings — Code of practice | Protected stairs, fire-fighting shafts and lobbies, when pressurisation is used in place of natural ventilation |
| EN 81-72:2020 | Firefighters lifts | Fire-fighter lift features |
Frequently asked
How do I use the Lobby pressurisation (lift / stair) calculator?
Open the tool, change the pre-filled example to your project, read the results, checks and worked steps as you type, then export the report, Excel and DXF.
Which codes and standards does the lobby pressurisation (lift / stair) follow?
It applies NBC 2016 Part 4, BS EN 12101-6:2005, BS EN 12101-13:2022, NFPA 92 (2021), NFPA 101:2021, ASHRAE Handbook of Smoke Control Engineering (2012) and others. Every result line shows the formula and the clause it comes from, and the report lists the standards applied.
What does it check?
Every run is marked PASS or CHECK against: Stair ΔP > lobby ΔP > floor; Lobby door force ≤ limit; Lobby → stair door force ≤ limit; Relief per lobby for the door-close case.
Is the calculator free to use?
Yes — running the calculation, reading the results, checks and clauses is free. One design credit unlocks the report, Excel and DXF exports for 30 days; the first design is free on sign-in.
Is this the same as a lobby pressurization calculation?
Yes. People also call it a fire fighting lobby pressurisation, a lift lobby pressurization fan, a BS EN 12101-6 lobby class B. It covers the same calculation under fire fighting design, with the Indian and international code regimes selectable.
Does it work with AutoCAD or ZWCAD?
Yes — with the free DesignLink CAD plugin the tool reads rooms, layers and selections from the open drawing and places its DXF output straight back into the plan; without the plugin you upload a DXF and download the result.